This project attempts to experimentally correlate the system entropy and entropy production rate in living systems with systems with system biological age. An entropy balance will be done on a living system (a fish) and all the entropy fluxes into and out of the system will be monitored. The entropy production of the system must be positive as dictated by the second law of thermodynamics, and may be minimized by certain environmental conditions. It is proposed that the entropy production rate of a living system directly affects its aging rate.